The present invention relates to apparatus and methods of severing and at least partially removing one or more covering layers on a filamentary core, such as an electrical wire, cable or optical fiber. More specifically, the invention relates to cutting/stripping apparatus, and methods of operation thereof, which include at least one first blade for rotary motion about the central axis of the workpiece, and at least two, second blades reciprocally movable along essentially linear axes, toward and away from the one another while remaining equally spaced on opposite sides of the central axis. In addition, the invention is directed to employment in apparatus which operates upon a succession of discrete workpieces, as opposed to more sophisticated apparatus capable of accepting a continuous supply of material (such as coated wire on a spool) and operating upon the material to form a succession of completed workpieces. The apparatus includes programmable, electronic control means with operator inputs to control parameters of the cutting/stripping operations; however, the invention is
Parent U.S. Pat. No. 6,588,302 discloses what is generally termed wire processing equipment having a single blade with a circular cutting edge surrounding an opening in the blade through which the covered wire or workpiece extends. A discrete workpiece, such as insulated wire cut to a desired length, is inserted axially into the machine until the end of the workpiece contacts a stop which is provided, as in many other prior art machines, by the surface of the blade. The wire is then fixed in position by a pair of clamping jaws and the blade is moved to bring the end of the wire into registration with the opening in the blade. The blade is then moved axially of the wire to position the cutting edge in a plane spaced a predetermined distance from the end of the wire. The blade is then moved in a circular path to orbit the wire axis as it cuts through one or more covering layers, such as insulation, shielding, or other materials. The apparatus includes a pair of so-called “gripping members” having straight, parallel edge portions which are moved by respective stepper motors toward and away from the workpiece axis to “forcibly engage” the outer layer thereof either before or after the blade has cut through the layer about its entire periphery. After the rotary cutting operation, and after engagement of the coating layer by the gripping members, the blade and gripping members are jointly moved axially of the wire to at least partially remove the severed portion, or slug, from the workpiece. The apparatus is programmable to receive operator inputs specifying the length of cut (i.e., the distance from a terminal end of the workpiece to the plane of rotary severing of the outer layer), the depth of cut (i.e., the radial distance from the outer surface of the covering layer to the terminus of the rotary cut), and, if desired, other operational parameters.
The apparatus of the parent patent thus provides a clean and complete cut, with precise dimensional control, of the outer layer of the workpiece and, with the assistance of the gripping members, permits efficient removal or partial removal of the severed slug. However, some wire processing operations do not require cutting of the outer layer about its entire periphery. For such operations it is sufficient that two blades (or more, if desired) move toward one another from opposite sides of the workpiece, severing the outer layer to the desired depth in portions of its periphery, and then move axially to complete the severing operation and remove the slug. Such apparatus usually operates faster, is easier to set up and is less expensive than the apparatus which cuts through the layer about its entire periphery. Therefore, most organizations which routinely process a wide variety of wires and cables, from easy-to-strip PVC hookup wire to those having harder and stronger layers such as Teflon, Kapton, Tefzel, as well as multi-layered cables such as coaxial cables, must purchase at least two types of machines for their production requirements. Obviously, this can become very costly.
Another type of wire processing apparatus is that known as “measure-cut-strip” equipment wherein wire or cable is taken from an essentially continuous supply, as from an appropriately supported spool, a fed axially into the apparatus which automatically proceeds to eject a succession of finished workpieces, cut to a desired length, with one or more covering layers cut to their respective thickness, each at a desired axial length from the end of the wire, and fully or partially stripped from the underlying layer. Although the aforementioned cutting and stripping is usually performed entirely by blades moving linearly toward and away from the axis of the workpiece, rotary cutting blades have been added, as a separate item or as an optional inclusion in the measure-cut-strip equipment itself. However, when rotary cutting capability is provided, it is used only to cut through covering layers and not through the entire workpiece, and is not capable of assisting in slug removal, as in the machine of the parent patent. Also, in measure-cut-strip apparatus having both rotary and linearly moving blades, the cutting planes of the two types of blades are not closely adjacent one another, but are offset along the axis of the workpiece by an appreciable distance. Measure-cut-strip equipment is both structurally and electronically sophisticated, typically costing many times the price of apparatus designed to accept and operate upon a succession of pre-cut wires or cables. For purposes of distinguishing the two different types of equipment, that to which the present invention relates will be termed “end stripping” equipment.